System and method for electroplating of hole surfaces

ABSTRACT

An electroplating method for plating internal surfaces of holes in metal products uses a needle anode associated with an XYZ or multi-direction positioning device to position the needle such that an insertion portion of the needle anode is centered over a hole and inserted to a predetermined depth in the hole, with a discharge end located a predetermined distance from the inner end of the hole. Plating solution is supplied to the needle anode and flows continuously during plating from the discharge end of the needle, through a gap between the needle anode and inner surface of the hole, and out of the open end of the hole into a drain. In one example, the metal object is a terminal of an electrical connector and the hole is a solder cup at a terminal end of the connector.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/151,532 filed on Jan. 9, 2014, the contents of which are incorporatedherein by reference.

BACKGROUND

1. Field of the Invention

The present invention relates generally to an electroplating system andmethod for electroplating a deposit of metal onto the internal surfaceof a closed or open hole or other cavity in a workpiece of conductive orpartially conductive material, and is particularly concerned withelectroplating holes or cavities of high aspect ratio, i.e. holes whichare deep compared to their diameter, such as solder cups of electricalterminals of electrical or hybrid electrical and optical connectors.

2. Related Art

Electroplating is a process that uses electrical current to reducedissolved metal cations to form a metal coating on an electrode.Conventionally, the process involves immersing the part to be plated andan anode (made of the metal to be plated on the part or a noble metal)in a bath or electrolyte solution containing one or more dissolved metalsalts as well as other ions that permit the flow of electricity. Thepart to be plated acts as the cathode of the circuit. As power issupplied to the circuit, metal atoms dissolve in the solution from theanode and are reduced at the interface between the solution and thecathode, such that they “plate” onto the cathode.

For example, electrical and electronic assemblies of instruments andcontrols are often supplied with electrical connections in the form ofmetal contact pins (and sockets). The inboard end (i.e., opposite themating end) of the pins (and sockets) are typically intended for solderconnections to electrical wiring. In particular, the solderingoperations include soldering the termination of an electrical wire intoa “cup” receptacle of the electrical connector thus forming theelectrical couple therebetween.

For high reliability applications, the ability to perform the solderingoperations (e.g., connecting conducting lines to connector terminals)must be assured, even after long storage of the assemblies andcomponents. To illustrate, if the pins are composed of nickel, stainlesssteels or other metals that strongly passivate by forming a toughsurface oxide layer, they become difficult to solder unless the surfaceoxide formation is inhibited. Thus, for high reliability applications,the soldering surfaces of such pins are usually provided in an oxidefree state that is protected by the pre-soldering application of a layerof gold plating, deposited by electrochemical or other means. If thegold plating is adequately thick (e.g., exceeding approximately 30micro-inches) and non-porous, it may prevent oxidation of the solderingsurface beneath it until the soldering operation is performed. The goldor other plating metal is typically dissolved into the solder alloyduring the solder operation and plays no further electrical ormechanical role in the formation of the joint, as long as theconcentration of the gold in the solder is not excessive.

Conventionally, the initial plating operations for the finishing of pinsfeaturing solder cups can be performed in several ways. As describedabove, pins can be electrodeposited with rack or barrel platingfixtures, wherein the pins or the connector assembly is placed in a bathof plating solution. The parts to be electroplated are connectedelectrically to an electrical power supply negative terminal (−). Thebath also contains anodes, connected to the power supply positiveterminal (+). The anodes may be of two types: consumable anodes andnoble material anodes. Consumable anodes are eroded by the passage ofplating current and dissipate into the solution, replacing the metalions that are deposited on the workpiece. Noble anodes consist ofplatinum, titanium or similar metal, possibly with coatings applied, orcarbon. They do not erode and do not replace the metal ions lost in theprocess. In this case, the deposited metal is supplied directly from thesolution. Electroless plating may also be used, in which the surfaces tobe plated are treated with a series of solutions that alternativelyactivate the surface and then deposit metal on it.

While electroplating in a plating solution bath is adequate for manyworkpiece geometries, electroplating a uniform deposit in deep hole isdifficult if the holes are deep compared with the diameter, referred toas a high aspect ratio. The current flow required for metal deposit ishampered by the longer travel distance required for it to reach thebottom of the hole. The current seeks the closer surface in the travelthrough the solution, rather that reach the deeper surfaces of the hole.The metal plating therefore plates more heavily on the surfaces near theentrance of the hole, leaving an insufficient deposit at the bottom. Thedeposition is further hindered by stagnation of plating solution deep inthe hole. Careful agitation and fluid flow is required to replenish thespent solution at the bottom of the hole after the latent metal has beendeposited from it. Moreover, these challenges are exacerbated in smallergeometries such as commonly found in electronics, electrical connectors,and the like, and solder cups of electrical connectors and the like areoften deep enough to present difficulty with obtaining a good metaldeposition to the bottom of the cup. This can result in a protectivelayer which is too thin or poorly adherent, as a result of the featuresand geometry of the high aspect ratio, deep hole or solder cup.

Additionally, re-plating of holes or cavities with poor or ineffectivecoating or solder layers in an electroplating bath is generally notfeasible for components already assembled into a finished product, suchas solder cups of pins already incorporated in an electrical instrumentassembly, because the complete assemblies cannot be subjected to thechemicals and temperatures typical of the electroplating process. Thus,such assemblies cannot be immersed in a plating tank or barrel.

SUMMARY

In one aspect, an electroplating method is provided for electroplatingan interior surface of a blind hole or cavity in a workpiece which isformed at least partially of metal or other conductive material. Themethod is designed for electroplating interior surfaces of a hole orcavity having a relatively high aspect ratio, i.e. where hole or cavitydepth is high relative to hole or cavity diameter or cross-sectionaldimension.

In one aspect, a method for electroplating an interior surface of aconductive cavity or blind hole in a workpiece is provided, which uses atubular anode or needle-like anode having a first end and a second end,the second end comprising a discharge outlet for discharge of platingsolution flowing through the tubular anode, a cathode contact configuredfor electrical connection to the workpiece or a conductive part of theworkpiece having a cavity with an interior surface to be plated, aplating power supply electrically connected between the anode andcathode contact, a positioning device configured for positioning atleast an end portion of the tubular anode through an open end of thecavity into an operative, coaxial position in the cavity spaced from theinterior surface and an inner end of the cavity to define a flow pathfor plating solution between the discharge outlet and inner end of thecavity, through an annular space between the interior surface of thecavity and the tubular anode, and out of the open end of the cavity, asupply of plating solution connected to the first end of the tubularanode, and a spent plating solution collection device positioned beneaththe open end of the cavity for collection of spent plating solutionflowing out of the open end of the cavity. In this method, platingsolution flows through the tubular anode, out of the discharge outlet,through an annular space between the tubular anode and an interiorsurface of the cavity to be plated, and out of an open end of the cavityalong the discharge flow path, and metal is deposited from the flow ofplating solution onto the interior surface of the cavity.

The tubular anode is of predetermined dimensions relative to the hole orcavity to be plated and an insertion portion of the tubular anode isconfigured to be inserted in the hole with an annular gap ofpredetermined width between the tubular anode and the opposing internalsurface of the hole or cavity and the discharge or second end of thetubular anode at a predetermined spacing from the inner end of the holeor cavity. The insertion portion may comprise a major portion of thelength of the tubular or needle anode.

In one embodiment, the method is designed for electroplating holes orblind bores of electrical terminals or pins, such as solder cups towhich electrical leads are to be soldered, but it may also be used forelectroplating of the inner end and sides of a closed or open hole orother cavity in any metal or part-metal object or workpiece. In a methodfor electroplating the inner surfaces of solder cups of plural pins of aconnector assembly, the spent plating solution collection devicecomprises a tray or basin of non-conductive material which is at leastpartially elastomeric, and has a base wall and a peripheral rim. Aseries of holes are provided at predetermined locations in the base wallfor sealing engagement around the outer surfaces of the respective pinsat a spacing below the open ends of the solder cups. In one embodiment,masking sleeves of non-conductive material engage over the outer surfaceof the respective pins between the open outer end of the pin and thebase wall of the basin. This masking arrangement may not be necessaryfor initial production plating, but is particularly advantageous whenre-plating solder cups in a finished electrical assembly, so as toprotect sensitive components in the assembly connected to the pins. Inthis case, exposure to plating solutions only occurs where it is needed,inside the solder cup, and all other surfaces of the pin are masked. Themasking sleeves may be separate from the base wall of the basin orformed integrally with the base wall. In one embodiment, an outletpassageway is provided in the base wall of the basin for directing spentplating solution away from the basin and into a suitable collection ordisposal device.

According to one aspect, a method for electroplating an interior surfaceof a blind hole in a workpiece formed at least partially of conductivematerial includes electrically coupling a current supply to theworkpiece, and electrically coupling the current supply to anelectroplating anode or needle anode, the electroplating anode includinga plating solution inlet, a discharge outlet, and a passageway extendingbetween the plating solution inlet and the discharge outlet. The methodfurther includes inserting a portion of the electroplating anodeextending up to the discharge outlet within the interior surface of theblind hole, and fluidly coupling a plating solution supply to thedischarge outlet via the plating solution inlet and the passageway,whereby plating solution flows from the plating solution supply throughthe internal passageway, out of the discharge outlet, and through thegap between the interior surface of the blind hole and the outer surfaceof the inserted portion of the anode out of the open upper end of thehole. An electric current is established between the interior surface ofthe blind hole and the electroplating anode through the plating solutionsuch that metal is liberated from the plating solution and attaches tothe interior surface of the blind hole.

The continuous flow of plating solution through the space between theneedle or tubular anode and the internal surfaces of the cavity and holeprovide a continuous source of metal so that the plating operation neednot be interrupted until metal deposition is complete. The method isparticularly helpful for plating of holes or cavities of high aspectratio (depth relative to cross-sectional dimensions) which are difficultto plate using conventional techniques. In one aspect, the method may beused for restoring or reworking electroplated nickel layers in soldercups at the ends of pins of connectors incorporated in completedinstrument assemblies when the original layers are too thin or poorlyadherent so that proper soldering to electrical wires or leads cannot beachieved. It may alternatively be used for production plating of deepholes in terminal pins or other metal objects, and is not limited torework of faulty components.

Other features and advantages of various embodiments will become morereadily apparent to those of ordinary skill in the art after reviewingthe following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of various embodiments of an electroplating system andmethod for high aspect ratio inner surfaces, both as to structure andoperation, may be gleaned in part by study of the accompanying drawings,in which like reference numerals refer to like parts, and in which:

FIG. 1 is a schematically illustrated vertical cross-sectional view ofone embodiment of an electroplating system for use in electroplating ahigh aspect ratio hole;

FIG. 2 is a schematically illustrated vertical cross-sectional view of amodified embodiment of an electroplating system for use in plating asolder cup of a pin of a connector unit;

FIG. 3 is a more detailed perspective view of one embodiment of theelectroplating system of FIG. 2;

FIG. 4 is a perspective view of the solder catch basin of FIG. 3 on alarger scale;

FIG. 5 is a perspective view of the syringe reservoir and needle anodeof FIG. 3 on a larger scale;

FIG. 6 is a schematically illustrated, enlarged side view of a typicalelectrical connector unit with solder cups which can be plated with theelectroplating systems of FIGS. 1 to 5, partially sectioned to show onerepresentative contact pin;

FIG. 7 is a perspective view of an exemplary 4-pin connector includingthe connector unit of FIG. 6 and a mating receptacle unit;

FIG. 8 is a perspective view of another known multi-pin plug andreceptacle connector with solder cups which may be plated by theelectroplating systems of FIGS. 1 to 5;

FIG. 9 is a flow chart of an exemplary method for electroplating highaspect ratio holes in connector pins or other workpieces using any ofthe systems of FIGS. 1 to 5.

DETAILED DESCRIPTION

The present disclosure relates to an electroplating system and method inwhich components having an internal surface or cavity with a high aspectratio may be more uniformly and thoroughly plated. Embodiments providefor a deposit of nickel, gold or other metal to be made onto thesurfaces on the bottom and sides of a closed or open hole or othercavity in a workpiece which may be a metal or partially metal object.For example, a nickel or gold layer can be deposited in the solder cupsof connector pins or terminals in a multiple contact connector unit. Thedeposit may be made during initial production of connector assemblies orthe like, or for reworking or restoring previously electroplated solderlayers in solder cups of finished electrical instrument assemblies orthe like which have insufficient nickel and/or gold deposition toprovide for soldering capability. The electroplating system and methodutilizes a unique hollow anode geometry that both provides for uniformplating current and plating solution replenishment. Here, theelectroplating system and method may also successfully restore theelectroplated nickel layers on affected pins on completed instrumentassemblies. Although applicable to electroplating during production ofelectrical pins and connectors, the electroplating system and method isgenerally applicable to production plating of solder cups in electricalconnector assemblies or deep holes or cavities in other metal products.

Although the embodiments described below and illustrated in the drawingsare concerned with electroplating the internal surfaces of blind holesor cavities, it will be understood that the same method and apparatusmay be used for electroplating an open hole or through bore, withsuitable plugging of one open end of the hole.

FIG. 1 is a schematically illustrated cutaway side view of oneembodiment of an electroplating system. In particular, the illustratedelectroplating system 100 is applicable to plating of an exemplary blindhole 31 in a workpiece 30 which is at least partially of metal or whichcontains metal components. Here, the blind hole 31 is generally a cavityhaving an open end 32 and a closed terminal end 33, and the interiorsurface 34 of the cavity may be electroplated using the system 100. Forexample, here, the blind hole 31 is illustrated as blind drill hole,wherein the interior surface 34 includes a cylindrical bore thattransitions into a shaped terminal end.

The disclosed electroplating system 100 is configured to plate theinterior surface 34 of a cavity that is deep and narrow (i.e., has asmall cross section). In particular, the cavity may have acharacteristic aspect ratio that is generally the ratio of its depth 35to its width 36. For example, here with the blind hole 31 represented asa drill hole, the depth 35 may be measured as the full diameter depth(neglecting nominal drill tip depth), and the width 36 may be measuredas diameter of the bore. According to one embodiment, the electroplatingsystem 100 may be configured for a cavity or blind hole having an aspectratio which exceeds 2.0, and particularly where the hole aspect ratioexceeds about 2.25. In addition, the electroplating system 100 may beconfigured for a cavity having a width or diameter 36 of less thanaround 6.4 mm (0.25 inch).

Additionally, this particular configuration is merely for illustrationpurposes, as the illustrated electroplating system 100 may be configuredfor any combination of singular or plural plating operations (e.g.,single or multiple blind holes 31), and individual or concurrent platingoperations (e.g., single or multiple needle anodes 140). Also, here andin other figures, various components and surfaces have been left out orsimplified for clarity purposes and ease of explanation.

Generally, the electroplating system 100 includes an electric current orplating power supply 112, a plating solution supply 120, an electricallyconductive tubular anode or “needle” anode 140 of conductive materialhaving a through bore or passageway 143, a positioning system or device150, and a spent plating solution drain or collection device 160, whichmay be a suitably sized drain tray or basin. The dimensions of theneedle anode 140 are selected based on the dimensions of the hole orholes 31 to be plated, and needle anodes of different dimensions may beprovided for connection in the electroplating system for plating holesof different sizes. In the illustrated embodiment, the plating solutionsupply comprises a reservoir 121 which may be manually filled withplating solution 90 or supplied with plating solution via a pump or thelike.

In one embodiment, system 100 is positioned as illustrated in FIG. 1with collection device 160 suitably supported in a fixed positionbeneath the needle anode 140, for example on top of a support surface(not illustrated). A workpiece 30 having one or more holes 31 to beplated is supported in a fixed position beneath the needle anode andabove spent plating solution collection device 160 by any suitablesupport mechanism, such as a product conveyor, insulated holding fixtureor the like. The workpiece 30 to be plated is not illustrated in detail,and only part of the workpiece including hole 31 is illustrated in FIG.1, but the workpiece may be any metal or partially metallic object ordevice having one or more high aspect ratio holes of conductive materialrequiring internal plating, for example solder cups of connector pin andsocket terminals of a connector device, vias in printed circuit boards,or the like.

The reservoir 121 is similar to the syringe of a needle, and has afunnel shaped outlet 123 suitably secured to an inlet end 141 of needleanode through bore 143, for example via an annular elastomeric washersealed between telescopically engaged ends of outlet 123 and inlet 141.In the illustrated embodiment, an optional heater 124 is located inreservoir 121 for heating the plating solution as needed, depending onthe plating solution used. The plating power supply has a positiveterminal connected to the needle anode via coupler 111, and a negativeterminal suitably connected via lead 115 to a conductive portion ofworkpiece 30.

The reservoir and needle anode are suitably mounted via a support systemwhich may comprise a support frame 151 which includes a platform orguide member 153 of non-conductive material such as plastic spacedbeneath reservoir 121 and having a guide hole or through bore 80 throughwhich needle anode 140 extends. The support system 150 is generally astructural support between the needle anode 140 and the interior surface34 to be electroplated and includes means for providing alignment,positioning, and relative motion or displacement between the needleanode 140 and the interior surface 34 to be electroplated. In theillustrated embodiment, the workpiece or object 30 having one or moreholes to be plated is supported in a fixed position in any suitablemanner during plating, while the needle is inserted into a suitableposition in hole 31 prior to each plating procedure. However, thesupport for workpiece 30 may alternatively be moved relative to theneedle anode 140 to position the anode in the hole in other embodiments.

The support frame 151 is not shown in detail, but it will be understoodthat any suitable support mechanism may be used for supporting theelectroplating system and workpiece to be electroplated during anelectroplating procedure. In the illustrated embodiment, the reservoirand needle may be mounted together on a suitable support frame. In oneembodiment, the support frame 151 is associated with an XYZ positioneror three axis positioning system 154 which drives the frame and attachedneedle anode 140 in X, Y and Z directions in order to position aninsertion portion 144 of the needle protruding out of guide hole 80inside a hole or cavity 31 of a metal object or workpiece 30 to beplated, as described in more detail below. In one embodiment, guidemember 153 may be part of an XYZ stage of XYZ positioner 154. Controller113 is connected to XYZ positioner or drive assembly 154 as well aspower supply 112 and heater 124 for controlling positioning of needleanode 140 and associated components prior to plating as well as turningpower supply 112 and heater 124 on and off as necessary. The controller113 may have a manual input for operator control of the plating process,or may be suitably programmed for automatic control of the system andpositioning of the needle anode, as discussed in more detail below.

In FIG. 1, the electroplating system 100 is illustrated with the lowerportion of the needle anode positioned inside hole 31 ready for aplating operation. The positioning device, which may be a conventionalXYZ positioning system, is configured or controlled to insert the needleanode centrally or coaxially to a predetermined depth into the hole 31as illustrated in FIG. 1, so as to leave a predetermined gap 38 betweenthe outlet end or discharge opening 142 of the needle anode 140 and theterminal end 33 of the blind hole 31) and a predetermined annular gap orspacing 39 between the outer surface of needle anode 140 and the innersurface 34 of the hole.

During plating operations, the needle anode 140 is mechanically coupledto the positioning device 150, electrically coupled to the electriccurrent supply 112, and is fluidly coupled to the plating solutionsupply 120. Also, during plating operations, the component to be plated(workpiece 30) is electrically coupled to the electric current supply112 such that the interior surface 34 of blind hole 31 operates as anelectroplating cathode. In FIG. 1, the electroplating system 100 isillustrated in a state where plating solution 90 is flowing through adischarge outlet 142 of the needle anode 140, around the needle anode140, and out of the open end 32 of the blind hole 31.

Power supply 112 may be a conventional electroplating DC power supply ofsufficient voltage and current for a given electroplating process. Inuse, power supply 112 forms an electroplating circuit with the needleanode 140 and workpiece 30 such that its blind hole 31 is theelectroplating cathode, as indicated in FIG. 1.

According to one embodiment, the electric current supply 112 may beremovably coupled to the needle anode 140. For example, the anodecoupler or contact 111 may be a contact band, such as a spring-loadedcontact from a small electrical connector pin (e.g., similar diameter asthe needle anode 140), which is modified to form an electrical couplewith the needle anode 140. A wire may also be soldered to the contactband to then connect to the DC power supply 112. Alternately, theelectric current supply 112 may be integrated with the needle anode 140(e.g., direct soldered connection). Additionally, the power supply 112may be turned on and off by electroplating controller 113, or may bemanually turned on and off by the operator, and may be included in thehousing or support frame 151 of the other electroplating componentsillustrated.

The plating solution supply 120 communicates with the inlet end 141 ofneedle anode for delivering the plating solution 90 for theelectroplating process to the needle anode 140. In the illustratedembodiment, plating solution 90 is gravity fed from reservoir 121through the through bore in needle anode 140, and the supply inreservoir 121 may be replenished manually or automatically via a pump orthe like. In alternative embodiments, plating solution 90 may beactively fed to the needle anode by a suitable solution deliverymechanism including one or more active devices such as pumps, controlvalves, switchable manifolds, etc. or any combination thereof.

According to one embodiment, the plating solution 90 may bepassively-fed to the needle anode 140. In the illustrated embodiment,the reservoir 121 is positioned above the needle anode 140 such that theplating solution 90 is gravity-fed to the needle anode 140. In oneembodiment, the reservoir 121 may be embodied as a large (e.g., 60 ml)syringe, open at the top, may be connected to the needle anode 140 via asmall silicone rubber tube (not illustrated) attached to the bottom ordelivery end of the syringe. The attached tube is fitted tightly orsealingly coupled over the interfacing inlet end of the needle anode140.

This configuration is beneficial in that it is both simple, costeffective, and agile, providing for ease of movement in the case pluralblind holes 31. In this configuration, an insertion portion of needleanode 140 may be easily maneuvered into and out of one or more blindholes 31. Moreover, the open top configuration allows for a manuallyrefreshed gravity feed that does not require being plumbed to a largetank, electrical pumps, and other large apparatus, which may bebeneficial in field or rework operations. In alternative embodimentswhere multiple blind bores in a workpiece are to be plated, a pluralityof needle anodes may be provided in a configuration matching that of theworkpiece bores, so that each bore is plated simultaneously rather thanmoving a single anode from bore to bore as described below in connectionwith the illustrated embodiments. However, the single needle anodesystem is more flexible since the positioning system can be programmedfor different numbers and arrangements of holes to be plated.

According to one embodiment, and as discussed below, plural platingsolutions 90 may be supplied by the plating solution supply 120. Inparticular, a first plating solution 90 may be used for a first platingoperation (e.g., pre-plate), and a second plating solution 90 may beused for a second plating operation (e.g., full plate). For example, thereservoir 121 may be a single-solution reservoir supplied with thedifferent plating solutions 90 separately as needed in the platingcycle. Alternately, the reservoir 121 may be a plural-solution reservoirconfigured to contain the different plating solutions 90 individually(e.g., in different compartments) with a flow separator such as aselectable flow valve to control flow from the different reservoirs.

The plating solution heater 124 may be controlled to maintain theplating solution 90 at a predetermined temperature or within apredetermined temperature range, so that it flows easily through theneedle anode and out through the annular space between the needle anodeand hole in which the anode is inserted. For example, the platingsolution heater 124 may include an immersion heater within the platingsolution reservoir 121 and configured to heat the plating solution 90directly. The plating solution heater 124 may alternatively comprise anexternal heater configured to indirectly heat the plating solution 90through the wall of reservoir 121 or another part of the platingsolution supply. In this way, the plating solution 90 may be maintainedat temperature above ambient conditions and provide for a greater rangeof plating solutions 90 and greater plating flexibility. The platingsolution heater 124 may be configured to maintain the plating solution90 at a high temperature (e.g., 75 degrees C.) during platingoperations. A temperature sensor (not illustrated) may be provided formonitoring plating solution temperature, with an output connected tocontroller 113.

The plating solution drain 160 may comprise a suitable drain basin orcatch tray positioned beneath workpiece 30 with the hole or holes to beplated, and positioned for receiving and collecting spent platingsolution 91 flowing out of the open upper end 32 of the hole to beplated during plating operations. The spent plating solution 91collected in catch tray or basin 160 or the like may be suitablydiscarded between plating operations. At least a portion of the platingsolution drain 160 may be non-conductive. For example, all or part ofthe plating solution drain or basin 160 may be made of a non-conductiveelastomeric material. Although the plating solution drain or collectionbasin 160 is schematically illustrated as a freestanding catch basin,the plating solution drain 160 may interface with the metal objecthaving a hole to be plated in certain embodiments, as discussed below inconnection with FIGS. 2 and 3.

The needle anode 140 is generally a tubular electrical anode forintroducing the electrical plating current whereby metal is depositedfrom the chemical plating solution. The hollow tube also serves to admitand replenish the plating solution 90 during the time that the platingis performed. In particular, the needle anode 140 includes a platingsolution inlet 141, a discharge outlet 142, an internal passageway 143,and an insertion portion 144. All or part of the needle anode 140 may bemade of a noble metal, such as platinum.

The plating solution inlet 141 interfaces with the plating solutionsupply and is configured to receive the plating solution 90 therefrom.The internal passageway 143 is within the needle anode 140 extendingbetween and fluidly coupling the plating solution inlet 141 and thedischarge outlet 142, and is configured to carry the plating solution 90therebetween.

As illustrated in FIG. 1, prior to starting an electro-plating procedurefor plating the inner surface of a hole 31, the XYZ drive 154 firstmoves the needle support frame 151 and attached components in horizontalX and Y directions until the needle anode 140 is located directly abovehole 31 and centered on the central longitudinal axis of the hole. Thediameter 146 of needle anode 140 is less than the diameter or horizontalcross sectional dimension of hole 31. In the case of a cylindrical holesuch as a solder cup of an electrical terminal, this dimension is thehole diameter, but in the case of a non-cylindrical cavity, thehorizontal cross sectional dimension is the minimum cavity width in adirection transverse to the insertion direction. The needle anode is ofuniform cylindrical shape in the illustrated embodiment, but inalternative embodiments, the insertion portion only may be of uniformdiameter, with other parts of the needle anode being of differentdiameter.

Once the needle anode is correctly positioned above hole 31, the XYZdrive 154 lowers the needle support frame 151 in the vertical or Zdirection until at least part of the insertion portion 144 of needleanode 140 extends into hole 31. The depth of hole 31 may be programmedinto controller 113 so that the discharge end or outlet 142 of needleanode 140 is positioned a predetermined distance 38 above the inner end33 of hole 31. The distance or gap 38 in one embodiment may be aroundtwo needle diameters above inner end 33, and is selected such that theplating solution can flow freely into the gap and around the outersurface of the needle through the annular gap 39 between the needleanode and inner surface of hole 31.

The insertion portion 144 is operated as the electroplating anode duringplating operations. In particular, the insertion portion 144 includes anelectrically conductive outer surface that is electrically coupled tothe electric current supply 112. According to one embodiment theinsertion portion 144 may be made of metal tubing. For example, theinsertion portion 144 may be made of a noble metal, such as platinumtubing. Moreover, as discussed above, the entire needle anode 140 may bea single metal tube or “needle”.

The diameter and length of at least the insertion portion of the needleanode 140 are determined based on the dimensions of the hole or cavityto be plated and different needle anodes in a range of differentdimensions may be provided for plating of different size holes. In onespecific example, a 0.026″ diameter needle of platinum or similarmaterial with a wall thickness of 0.006″ was used to plate the insidesurface of a solder cup of nominal inside diameter 0.065″ and a depth of0.210″. This provides an annular space or gap 39 between the needleanode and hole internal surface of around 0.02″, with the needle radiusbeing around 0.6 of the hole radius. The depth/diameter or aspect ratioof the hole was 3.2. The needle plating system may be used to plate anyholes having relatively high aspect ratio (i.e. deep and narrow holes),and becomes highly advantageous when the aspect ratio exceeds about 2.In general, the needle anode plating system may be useful for plating ofholes with aspect ratios in the range of around 2 to 4, with holediameters in the range from around 0.01 inches to around 0.25 inches(existing plating techniques can be used for holes of larger diameterthan this), and needle anode diameters in the range from around 0.006inches to around 0.125 inches. In the above example, the discharge endof the needle anode was positioned 0.050″ inches above the bottom of thehole, or about 2 needle diameters, or slightly less than 1 cup diameter.The ratio of the needle radius to the cup or hole radius (Rneedle/Rcup)in one embodiment is not less than 0.1, with a practical range of 0.1 to0.6.

Positioning of the needle anode centrally at the appropriate depth inhole 31 may be accomplished automatically via controller which issuitably programmed with the fixed hole position or positions anddimensions, or may be accomplished via a manual alignment tool, guide,or blank, an alignment sensor, and alignment meter, micrometer, or thelike.

Additionally, the positioner 154 may be configured to providetranslational motion between a plurality of holes to be plated in asingle workpiece or product 30 or multiple such products moved intoposition on a positioning frame or conveyor. For example, in addition tomoving into and out of a first blind hole 31, the positioner or XYZdrive 154 may also move the needle anode from hole to hole and lower theneedle anode into position in each new hole, for example, in ahummingbird-like manner. Multiple blind holes 31 may be accommodated inthis or a like manner.

According to one embodiment, the positioning device 150 may provide forprecision motion and positioning in plural directions. In particular,the positioning device 150 may comprise a plural-axis machine tool (e.g.x-y-z machine, CNC machine, etc.). For example, the support structurefor the needle anode may be fixed to an XYZ head or stage of aplural-axis machine tool such that it is movable through manual orautomated control. The plural-axis machine tool may include x-axis andy-axis drive micrometers, which may be configured for moving the needleanode 140 into position over each blind hole 31 for plating, and mayfurther include a z-axis drive micrometer configured to move the needleanode 140 into and out of each blind hole 31 for plating, as describedin more detail below in connection with FIG. 4.

The electroplating method will now be described in more detail. Once theinsertion portion 144 of the needle anode is properly positioned in hole31, the power supply 112 is turned on and plating solution 90 issupplied from reservoir 121 to the needle anode 140. An on off valve(not illustrated) may be provided between reservoir 121 and needle anode140 to control supply of plating solution to the hole via needle anode140. Plating solution 90 flows through the bore 143 of needle anode 140,out of the discharge end 142, and then outwardly from the inner end 33of the hole and upwardly through the annular gap 39 between the anode140 and inner surface of the hole, as illustrated by the arrows. Platingsolution then flows out through the open end 32 of the hole andoutwardly, as indicated by the arrows, over the edge of workpiece 30 anddownwardly into the spent plating solution collection basin or drain160.

The basic system and method of FIG. 1 may be used for production platingof holes in products such as solder cups of metal contact pins orsockets or connectors including metal contact pins and sockets prior toassembly into a final product, or other metal products having highaspect ratio holes or bores to be plated, such as printed circuit boardsor the like. However, this system is only appropriate where the exposedouter surfaces of the product are not sensitive or susceptible to damagefrom plating solution flowing over those surfaces after exiting hole 31,or other components assembled within the product are not susceptible todamage due to differential voltages between the part being plated and aninstrument case of the final product.

FIG. 2 illustrates an embodiment of a modified electroplating system 200which allows for protection of outer surfaces of pins of plug orreceptacle contacts of a connector unit 50 while the solder cups arere-plated. FIG. 3 is a more detailed perspective view of a manuallyoperated embodiment of the system of FIG. 2 having three axispositioning slides, as described in more detail below, while FIGS. 4 and5 are enlarged views of the collection basin 210 and the reservoir andneedle anode of FIG. 3. The systems of FIGS. 2 and 3 may be used forproduction plating of solder cups in a connector unit 50 alone, or maybe used for reworking or re-plating of solder cups in a completedinstrument or electrical assembly including connector unit 50 as well asother electrical components and circuitry within a housing or enclosure.Where system 200 is intended for reworking or re-plating of solder cupsin a completed instrument, it is also modified to provide protectionagainst differential voltages imposed between any of the connector pinsor conductors 52 or between the pins and the instrument housing. Anyuncontrolled differential voltages could damage sensitive electronicswithin the instrument housing, either rendering the instrumentinoperative or liable to subsequent failure. Since the electroplatingprocess is an electrical process, uncontrolled differential voltages of1 to 6 volts could potentially be imposed, which is unacceptable for anysensitive components within the finished instrument module incorporatingconnector unit 50. Apart from the modifications for shielding outersurfaces of the pins or terminals having solder cups to be re-plated andfor control against differential voltages or electrostatic damage,components of the system of FIG. 2 are otherwise identical to those ofFIG. 1, and like reference numbers are used for like parts asappropriate.

For information purposes, typical connectors or “plug” units 50 of aconnector 55 are illustrated in FIGS. 6 to 8, with the mating connectoror receptacle unit 57 of connector 55 illustrated alongside or alignedwith the plug unit in FIGS. 7 and 8. Each connector unit has a forwardend 68 designed for mating engagement with the forward end of the matingconnector unit, and a rear end 69 where projecting rear ends of theconductors 52 projected for attachment to wires of electrical cables.The electroplating systems of FIGS. 1 to 3 may be used for productionplating solder cups 60 at the outer ends of conductors or conductiveshafts 52 which extend through a dielectric body or insulator 54 inconnector shell 51 and terminate at pin or socket terminals 71, 72 atthe mating ends of such connector units. Electroplating may be doneeither during production, before or after assembly of such connectorunits into a final instrument housing, or as a rework of faulty soldercups after final production.

Electrical connectors of the type illustrated in FIGS. 6 to 8 are wellknown and may have any number and different arrangements of electricalpins and sockets, and FIGS. 7 and 8 illustrate examples of two suchconnectors. During assembly of such connectors into a final product orassembly, the solder cups 60 are soldered to wires or leads 53 of anelectrical cable 69, for example as illustrated in FIG. 6. The cable maybe inside an instrument housing to connect to a component within thehousing, with the terminal ends exposed for connection to a matingconnector unit at the end of a cable such as a subsea cable or the like,for electrical communication between the instrument housing and anotherstation or module.

FIG. 7 is a perspective view of an exemplary 4-pin connector. Inparticular, illustrated are embodiments of a two part underwaterconnector 55 for connecting optical, electrical, or electro-opticalcables. The parts comprise a fixed bulkhead or “plug” unit 50 and areceptacle unit 57 for releasable mating engagement with the plug unit.However, it will be understood that the connectors may be modified formaking hybrid electro-optic connections. Additionally, this embodimentof a 4-pin connector illustrated by way of example only, and it will beunderstood that the connector may alternatively be designed for making agreater or lesser number of connections, depending on the application,with FIG. 8 illustrating a connector with a greater number of pins orconnections. In the connectors of FIGS. 6 to 8, the electrical terminalsor conductors 52 extend or project out of the rear end of body 54, whichmay be of glass sealed to the respective conductors 52. Solder cups inthe projecting ends of conductors 52 of both plug 50 and receptacle 57may be electroplated with the electroplating systems of FIG. 1, 2 or 3,with FIGS. 2 and 3 being more appropriate when the connector isassembled into a finished product, and thus includes additionalelectronics and sensors assembled with the conductors or electricalterminals 52 which require protection and shielding from stray voltagesduring plating. However, the electroplating system and method describedherein is not restricted to electroplating of solder cups of harshenvironment connectors, but may be used for electroplating solder cupsof any type of electrical connector, as well as holes in other productssuch as printed circuit boards, as discussed above.

The illustrated electroplating system 200 of FIG. 2 has a needle anode140 as in FIG. 1. FIG. 2 illustrates three representative solder cups 60engaged with system components prior to plating. Here, each electricalconductor 52 includes a solder cup 60 similar to the blind hole 31discussed above. In this configuration, electroplating system 200 mayprovide for pre-soldering plating operations or production plating, oralternatively for re-plating of faulty solder layers in solder cups ofpreviously manufactured devices which do not support soldering ofelectrical leads. Although three solder cups are visible in theillustrated embodiment, it will be understood that other solder cups ofthe connector may be hidden in the side view of FIG. 2, and the samesystem may be used for electroplating a greater number of solder cups ofconnector units having a greater number of conductors providing contactpins or receptacles at the opposite end to the solder cups, where thesolder cup ends of the electrical conductors project out of the rear endof dielectric body or insulator 54.

Additionally, and as above, this particular configuration is oneembodiment, and the illustrated electroplating system 200 may beconfigured in other embodiments for any combination of singular orplural plating operations (e.g., single or multiple electrical terminals52), and individual or concurrent plating operations (e.g., single ormultiple needle anodes 140). For illustration purposes, portions of theelectroplating system 200 have been modified and/or exaggerated forclarity purposes and ease of explanation.

Generally, the electroplating system 200 includes the electric currentsupply 112, the plating solution supply 120, the needle anode 140, andthe positioning device 150 as discussed above in connection with thefirst embodiment. However, unlike the previous embodiment, thecollection device for spent plating solution is not simply positionedbeneath the device having holes to be plated, but is instead configuredfor engagement over the projecting ends 63 of the electrical terminalsor conductors 52. In this embodiment, the collection device comprises acatch basin or collection tray 210 having a base wall 212 and peripheralrim 214. The entire basin 210 or at least base wall 212 is formed of asemi-rigid elastomeric and non-conductive material such as rubber. Basewall 212 has a plurality of openings or through holes 215 of slightlysmaller diameter than the diameter of terminals 52, and the number andarrangement of holes is designed to match that of the terminals 52. Theholes 215 are sealably engaged over the respective terminals 52 as seenin FIG. 2 such that the base wall 212 is positioned just below the loweror inner ends 62 of the respective solder cup. In one embodiment, thecollection basin 210 is formed from a rubber or other elastomericmaterial of sufficient rigidity, such as plumber's rubber or otherelastomeric, non-conductive material of around 80 Durometer. Catch basin210 also has an outlet or drain opening 216 for flow of spent platingmaterial out of basin 210 into discharge passageway 218.

In addition to the catch basin or collection tray 210, the system 200further comprises a plurality of masking sleeves 220 configured forsealing engagement over the portions of terminals 52 projecting upwardor outward through the holes 215 in the base wall 212. These sleeves arealso formed of elastomeric, non-conductive material and have diametersslightly less than the diameters of the respective terminals orconductors 52, so that they are a close sealing fit over the outersurface of the conductors surrounding solder cups 60. The catch basinholds the connector unit in a fixed, stable and stationary positionduring electroplating and may be supported in any suitable supportfixture or mounting device (not illustrated). The masking sleeves 220may be formed integrally with the base wall 212 of basin 210 or may beseparate sleeves which slide on over the respective projecting ends ofconductors. The sleeves are designed to extend from base wall 212 up tothe open ends 65 of the respective solder cups 60. The catch basinshields lower portions of the conductors 52 from the plating solutionand insulates the conductors. The sleeves 220 shield the outer surfacesof the projecting ends of shafts 52 to prevent deposition of metal fromthe plating solution flowing out of the open ends 65 onto the outersurfaces of the solder cup ends of conductors 52.

In this embodiment, needle anode 140 or its insertion portion 144 isconfigured for electrical terminals 52 with solder cups 60 which havedimensions, aspect ratios, and features within the ranges describedabove in connection with the blind holes 31 described above inconnection with FIG. 1. According to one specific example, the needleanode 140 was a platinum tube of chemically pure material with a wallthickness of approximately 0.006 inch and a diameter of approximately0.026 inch along its tubular length, and is designed for use in platingoperations in which solder cups 60 have a nominal inside diameter of0.065 inch and a depth of 0.210 inch and having an aspect ratio of 3.2.The needle anode may be of other noble metal materials, and may be ofdifferent dimensions depending on the parameters of other solder cups tobe electroplated. As discussed above, the needle plating system may beused to plate solder cups having relatively high aspect ratio (i.e. deepand narrow holes), and becomes highly advantageous when the aspect ratioexceeds about 2. The system may be provided with a plurality of needleanodes of different diameter and the appropriate diameter anode may beselected for attachment to the outlet of reservoir 121 depending onsolder cup size. As discussed above, the needle anode plating system maybe useful for plating of solder cups with aspect ratios in the range ofaround 2 to 4.

Each solder cup 60 has an interior surface generally defined by an innerwall 61 and a cup bottom 62. Inner wall 61 has a circular cylindricalshape, and each cup bottom 62 is of conical shape, for example, asformed by a drill.

In the illustrated embodiment, each electrical terminal or conductor 52is separately connected to the plating power supply via current supplylead 132 which has plural contacts or connections 131 to the respectiveconductors 52 at a location beneath catch basin 210. Since eachelectrical terminal or conductor 52 is made of conductive metal alongits entire length, the cathode connection or contact 131 may be attachedto any exposed outer surface of the electrical terminal 52, for exampleat the pin or receptacle contacts at the opposite end of the connector50. In the latter case, the contact or connection from lead 132 to therespective conductors may comprise a socket where the mating ends of theconductors are configured as conductive pin contacts, and a pin wherethe mating ends of the conductors are configured as conductive sockets.

In one embodiment, each electrical terminal 52 to be plated mayconnected to the power supply negative terminal (making it the cathode)at the time it is plated, and then disconnected when the solder cupplating is completed. For example, each electrical terminal 52 may beindividually wired to the electric current supply lead 132 as it isplated, and then unwired. Alternatively, plural electrical terminals 52may be simultaneously wired to the electric current supply lead 132during plating operations, and then unwired. The terminals or conductors52 may be connected together by wrapping a bare copper wire around eachone, then leading the wire to the next pin and wrapping it, and so on,until all conductors 52 are daisy chained together,

The wire or lead 132 is additionally connected to common node 134 whichis grounded to the connector body or housing 51 to insure that all pinsor conductors 52 are at zero voltage potential relative to each otherand to the sensor housing. This helps to protect components within theelectronics module against damage or failure by not imposing anydifferential voltages between any of the pins or between any of the pinsand the housing. Because the plating process is an electrical process,voltages from 1 to 6 volts could be imposed without such an arrangement,which is unacceptable for sensitive devices. By wiring the conductors orpins 52 together and to the housing, this possibility is reduced. Wherethe connector 50 is assembled into an electronics assembly or modulecontaining sensitive components such as sensors, the electricalterminals 52 may be electrically coupled or grounded to the housing ofthe electrical component. Furthermore, the common node or junction 134may be electrically coupled to a ground 70 (grounded) such as an earthground or a building ground of the plating shop, to eliminate or reducethe risk of electrostatic damage, maintaining common node 134 at zerovoltage relative to each constituent electrical coupling. Thisarrangement also helps to avoid or reduce the risk of stray voltagesfrom the power supply. The insulating shield 210, 220 around the pinsisolates the electrified plating solution from the wiring and housingalso helps to avoid or reduce the possibility of voltage differences inthe bath.

The additional grounding features may be particularly advantageous whenoperating on assemblies having sensitive instrumentation, for exampleduring rework operations. In particular, since the plating process is anelectrical process, uncontrolled voltages on the order of 1 to 6 voltscould be imposed in the system. While this may inconsequential for mostplating operations, this may be unacceptable for electroplating asensitive device. Moreover, the damage could be latent, meaning notdetectable by any testing, yet causing premature failure. Here, byprotecting against any differential voltages between any of the pins orbetween any of the pins and the housings, the ongoing reliability of theelectrical component may be protected despite the plating process. Forexample, by wiring the pins and the housings together, potential fordamage from uncontrolled voltages may be reduced. Also, by wiring to anearth or building ground, the possibility of electrostatic damage (e.g.,from stray voltages from the power supply) may also be reduced.

In one embodiment of electroplating system 200, reservoir 121 was alarge 60 ml syringe, open at the top, connected to the needle anode 140,and kept at least half full by topping it off as it drained out. Theflow was gravity fed in one embodiment, but constant feed via a pump orthe like may be provided in other embodiments. In one example, the flowrate of plating solution was about 30 ml per 5 minutes, which produced aconstant “upwelling” type of flow out of the top of the cup beingplated. This is sufficient to flush air and bubbles out of the flow pathwithout spewing out of the cup. In one example, electrical current wasturned on when the flow of plating solution started. This arrangementavoids a continuous liquid path to large apparatus or pumps or tankswhich would then become electrically connected to the plating supply.The syringe reservoir 121 is compact, simple and electrically insulated.

In one embodiment, two different plating solutions were used. The firststep is a nickel “strike”, which deposits a very thin layer of around 5micro inches on the internal surface of the solder cup 60. It alsoelectrically cleans, etches and prepares the surface. It is immediatelyfollowed with a nickel sulfamate process plating that builds a thickerlayer, up to 150 micro inches. This process is used because thesulfamate deposition rate is much faster. It takes a few minutes, wherethe strike would require hours to achieve the same deposit. The samesyringe was used first for the strike solution, until all cups wereplated, then the syringe was refilled with the sulfamate solution, andall cups were plated. The cups were kept filled with deionized (DI)water between steps to avoid drying out that could leave oxides andcontamination. The sulfamate solution must be maintained at a hightemperature, maybe 75 degrees C. To avoid cooling off in the syringe,immersion heater 124 inside the syringe is used to keep the solutionwarm.

FIG. 3 is a perspective view of one embodiment of the system of FIG. 2in more detail, and like reference numbers are used for like parts, asappropriate. The XYZ positioner in the embodiment of FIG. 3 is a threeaxis positioning system having x, y and z positioning slides 310, 312and 314, respectively, each having a respective x, y or z axismicrometer drive 315, 316, 317, respectively. The reservoir 121 andneedle anode 140 are supported on the z-axis positioning slide orplatform 314 via support 150 and guide platform 153, respectively. Thesystem of FIG. 3 is designed for manual adjustment of the x, y and zpositioning slides, but it will be understood that a correspondingautomated system could be provided with controller 113 as in FIG. 2connected to x, y and z axis drives and programmed for controllingmovement of each of the three slides to position needle anode 140 ineach solder cup 60 to be plated. In FIG. 3, the XYZ positioner andplating system and a sensor assembly 50 to be replated are supported ona suitable table 318 or other horizontal support surface, with theconnector end containing solder cups 60 facing upwards towards theneedle anode. The table may have an opening through which part of sensorassembly or instrument module 50 extends, and module 50 may be clampedin position by any suitable fastener or clamp means.

The plating solution catch basin 210 is engaged over the projecting endsof the conductors as illustrated in FIG. 2. In this case, the connectorunit has a circle of eight conductors or terminals with solder cups, butother numbers and arrangements of solder cups may be present in otherdevices with holes or solder cups to be re-plated. The catch basin 210for this particular solder cup arrangement is illustrated in more detailin FIG. 4, and the lower wall 212 has openings for engagement over therespective terminals or conductors below the solder cup ends, as well assleeves 220 extending upward from the wall for sealing engagement overexposed outer surfaces of the conductors within basin 210. The drainoutlet pipe 218 may be secured to a suitable hose for directing spentplating solution into a suitable container for disposal or recyclingpurposes

As in the embodiment of FIG. 1, needle anode 140 is supported and guidedby a plastic part or guide plate 153 attached to the Z-axis positioningslide 314 that also holds the syringe 121, for example as illustrated inFIG. 3, so that these parts all move together. In other words, thesyringe, needle, heater when used, needle support, syringe support, andelectrical contact band 111 with wire all move together. FIG. 5illustrates the syringe shaped reservoir 121 and needle anode 140attachment in more detail. As illustrated in FIG. 5, the outlet end ofreservoir 121 and the inlet end of needle anode 140 are secured togethervia tubular coupling 320 of flexible tubing.

The needle anode moves from cup to cup hummingbird style. At the end ofeach plating procedure, the needle anode is withdrawn well above the topof the solder cup using the z-axis micrometer drive 317. The x and yaxis drive micrometers are then used to move the needle into positionover the next cup for plating. The needle is carefully lowered into thecup, and viewed from several angles to insure that it is centered. Theindicated position from the micrometer readout is recorded to facilitaterepositioning later. An ohm meter may be connected between the groundedpins and the needle contact wire.

When the needle anode is properly positioned and centered over each newsolder cup to be plated, it is lowered into the cup using the z axismicrometer of XYZ drive 154 until it touches the bottom of the cup, asindicated by the ohm meter indicating electrical contact. The needleanode is then withdrawn by 0.050″ using the z axis micrometer. Thissetting is recorded for future use. It only varies slightly from pin topin for a given sensor. The needle stand-off distance is thus about twoneedle diameters as discussed above.

When in position, the syringe is filled, the power is turned on and theplating solution 90 flows through the anode, out of the discharge end142, through the gap between the needle anode and inner wall 61 of thesolder cup, and out of the open upper end of the cup. As indicated bythe arrows in FIG. 2, spent plating solution then flows down the outsideof the cup into catch basin or tray 210, and is discharged via outlet216 to discharge passageway 218 for subsequent collection or disposal.

Once the cup surface is plated to a sufficient thickness, the needle iswithdrawn to well above the cup and moved to the next position. Theprocess is repeated for the next solution and plating step, so that allcups are plated twice, once for strike and once for sulfamate. The aboveprocess, including handling of the solutions, positioning the needleanode, and starting and stopping flow through the needle anode and powersupply to the anode and cathode may be automated and computer controlledin alternative embodiments, and set to run by different programs forconnectors with different pin locations, numbers, and patterns.

The process described above may be automated in other embodiments, anddifferent connectors with different pin positions may be separatelyprogrammed and automatically plated. The plating could be locallyapplied by suitable programming only to solder cups with defectivesolder layers, as needed for soldering or corrosion protection, limitingthe amount of gold, chromium, nickel used, and thus limiting spills,vapors and disposal of waste. The above plating method, whethercontrolled manually or automatically, avoids the need to immerse theentire glass sealed assembly of a finished electrical assembly instrongly ionic chemical plating solutions that tend to infiltrate tinynooks and crannies where they sometime cannot be cleaned away. If aplating process reduces the electrical insulation between the pins andbody, the article is a reject. In the normal plating process, all thewires go in the plating tank in place on the article, and get platedtoo, and cause irregular surface finish where they touch the pinsurface. The process in the above embodiment also removes the concern ofentrapped air bubble causing erratic plating coverage in the cup, andmore rejects or costly rework. Inspection requirements might also berelaxed.

For connectors in which the solder cup ends of the electrical terminals52 are recessed within the connector body 51, essentially the sameplating system and method may be used to plate the solder cups. In thatcase, the region between the connector body 51 and the outer ends of thesolder cups of the electrical terminals 52 may be filled in with wax,putty, asphalt or other non-conductive, removable sealant up to the openends of the cups during the plating operations, with the catch basin orcollection tray having an opening secured around the connector body. Theneedle anode can then be lowered into the respective solder cupssequentially and positioned for plating flow in exactly the same way asdescribed above in connection with FIG. 2.

FIG. 9 is a flow chart illustrating one embodiment of a method forelectroplating high aspect ratio inner surfaces such as solder cups orholes. In particular, the method is directed toward electroplating aninterior surface of a blind hole in a metal object such as a solder cupin an electrical terminal, as described above in connection with FIGS.1, 2 and 3. This method may be applied to rework or repair of existingparts or to production of new parts.

The shape and positioning of the needle anode, as well as themethodology can aid to get a more uniform deposit. This is particularlyadvantageous, as obtaining solution flow in the solder cup is difficultwith conventional methods because the solder cup is only open at oneend. Furthermore, bubble entrapment in the solder cup may also restrictuniformity of the deposit.

In the method of FIG. 9, the needle anode 140 is first positioned by theXYZ positioner 154 at a centered position over a solder cup to be platedand then positioned in the cup with discharge end 142 spaced apredetermined distance from the closed end of the cup or hole, asdescribed above in connection with FIGS. 1 to 3 (step 910). Once theneedle anode is in the correct position in a cup 60, the power supply tothe anode and conductors 52 is turned on (step 930), and platingsolution 90 is supplied continuously from reservoir 121 to the inlet endof the needle anode (step 920). The electrical connections may beelectrically connected to a ground or grounded as described above, forexample, at a common node, to eliminate or reduce the risk of impositionof damaging differential voltages on the electrical terminals and otherinstrumentation as above by maintaining them all at the same potential.

Plating solution flows continuously during plating through the innerpassageway or bore through needle anode, out of discharge end, aroundthe anode through the gap between the anode and inner wall 61 of the cupto be plated, and out of the open upper end 65 of the cup, thentraveling down around the protective sleeve 220 covering the outersurface of the sleeve into plating solution drain or collection basin214 (step 950). Spent plating solution is discharged via outlet 216 anddischarge passageway 218 to a suitable collection and disposal device(step 955).

Flow of plating solution through the cup is continued (step 960) untilsufficient time has elapsed for an electroplated layer of the desireddepth to be deposited on the inner surface (cylindrical wall 61 andinner end 62). Plating flow from reservoir 121 may be provided by pump,gravity feed or other means, as discussed above. The plating operationfor the first cup or hole is then terminated (step 965), the powersupply between the needle anode and terminal (cathode) is turned off,and the supply of plating solution to the needle anode is terminated.The needle anode 140 is then retracted from the hole or cup to alocation well above the top of the solder cup using, for example, thez-axis micrometer drive of the XYZ positioning device (step 970). Ifthere are more holes or solder cups to be plated (step 980), the processis repeated for the next hole or cup to be plated, with the needle anodemoved by the XYZ drive or positioning device 154 from solder cup tosolder cup hummingbird style. Once all holes or cups which need to beplated are finished, the process ends (990).

The above method may be manually controlled by an operator oralternatively may be automated and computer controlled, and set to runby different programs in a system controller for example. The automationmay be programmed for different numbers and locations of solder cups ofelectrical terminals or holes of a similar nature in other products.

According to one embodiment, the step of supplying plating solution mayalso include heating the plating solution. In particular, the platingsolution may be heated while plating operations are ongoing. Forexample, the plating solution may be heated using an immersion heater,or other heater as described above, and maintained at a predeterminedtemperature or within a predetermined range in steps 950 and 960.

The electric current established in the plating solution between theinterior surface of the blind hole and the electroplating anodeliberates metal from the plating solution, which is then deposited ontothe interior surface of the blind hole 960. Gases or other chemicalsliberated at the insertion portion of the needle anode are swept awayfrom the plating area by the continuous flow and replacement of theplating solution supplied by the needle anode. The needle anode isformed of material which is not consumed by the electrochemical actionof the plating in this step, such as a noble metal, coated ceramic orthe like. Thus, the plating solution is the source of the metal to bedeposited. Furthermore, the continuous flow and replenishment provides acontinuous source of metal for plating, so that the plating operationneed not be interrupted until the metal deposition is complete.

FIG. 9 illustrates a plating process in which a single plating layer isapplied to the hole surface, but alternative plating methods may includea two or more stage plating process in which different plating solutionsapply two or more layers to a single component to be plated, asdescribed above. In particular, a pretreatment plating may be appliedprior to the actual or primary plating. Examples of the plural solutionsmay include Wood's Nickel strike, and sulfamate nickel. The strike maybe used for surface preparation and a thin nickel deposition. Thesulfamate solution provides for plating to the final desired thicknessat a more rapid deposition rate. For example, the first platingoperation may be with a nickel “strike”, which deposits a very thinlayer of approximately 5 microinches. This plating may also electricallyclean, etch, and prepare the interior surface. The first platingoperation may be immediately followed with a nickel sulfamate processplating, which builds a thicker layer of up to approximately 150microinches. The two step process is advantageous because the sulfamatedeposition rate is much faster, taking a few minutes, where the strikewould require hours to achieve the same deposit.

In a two stage plating embodiment, the same plating solution or syringemay be used first for the strike solution, until all solder cups areplated, then the syringe may be refilled with the sulfamate solution,and a second plating layer is then applied to all solder cups in turn.The solder cups may be kept filled with deionized (DI) water betweenplating rounds to avoid drying out, which could leave oxides andcontamination.

In addition to the benefits associated reworking or repairing connectorsthat are already assembled into components, the electroplating systemsand methods described above also offer several significant advantages inproduction. For example, if the process were automated, differentconnectors with different pin positions could be separately programmedand automatically plated, with each connector positioned in turn at aplating station 100 or 200 by a conveyor-like system. Also, since theplating could be locally applied only to where needed for soldering orcorrosion protection, the amount of gold, chromium, nickel used could belimited. To illustrate, instead of 50 gallons or more of toxic liquidbubbling in multiple vats using conventional plating bath methods, thesystem and method described above may only require a few gallons ofplating solution, thus limiting spills, vapors and disposal of waste.

Also, where the electrical terminals are already installed in glasssealed assembly, this system and method avoids the need to immerse theentire assembly in strongly ionic chemical plating solutions that tendto infiltrate tiny nooks and crannies where they sometimes cannot becleaned away, resulting in a defective assembly which is then rejected.Although embodiments of the electroplating system 100, 200 are describedabove for electroplating (nickel plating in this case), the method andsystem is generally applicable for all plating, electro-cleaning, andelectro-polishing applications for deep or high aspect ratio holes orcups.

The elimination of submersion of a product to be plated in a platingbath avoids inadvertent plating of support structure, or the overplatingof the component in which the electrical terminals are installed. Forexample, in conventional bath plating, the cathode lines go in theplating tank along with the article, and are also plated, which maycause irregular surface finish where they touch the electrical terminalsurface (e.g., using a conductive support tray). Also, the continuousflow plating process using a needle anode as described above helps toavoid air bubbles described above. Also, inspection requirements mightbe relaxed. In short, the system and methods disclosed herein present anew approach to electroplating which allows plating of areas which aredifficult or impossible to plate uniformly using existing techniques,such as deep, high aspect ratio holes, bores, or cups in metal productssuch as connector terminals.

The above description of the disclosed embodiments is provided to enableany person skilled in the art to make or use the invention. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles described herein can beapplied to other embodiments without departing from the spirit or scopeof the invention. Thus, it is to be understood that the description anddrawings presented herein represent a presently preferred embodiment ofthe invention and are therefore representative of the subject matterwhich is broadly contemplated by the present invention. It is furtherunderstood that the scope of the present invention fully encompassesother embodiments that may become obvious to those skilled in the artand that the scope of the present invention is accordingly limited bynothing other than the appended claims.

We claim:
 1. A method of electroplating an interior surface of a hole ina workpiece, comprising: supporting a workpiece having at least one holeto be plated beneath a plating system including a tubular electrode ofconductive material having at least an insertion portion extending to adischarge end of the tubular electrode which is of cross-sectionaldimensions less than the cross-sectional dimensions of the hole to beplated, at least part of the workpiece including the hole being ofconductive metal; moving the tubular electrode relative to the workpieceto a predetermined horizontal position spaced above and centered on thehole; moving the tubular electrode vertically relative to the hole intoa plating position in which the insertion portion extends into the holewith the discharge outlet spaced a predetermined distance above an innerend of the hole; connecting a power supply between the tubular electrodeand conductive metal of the workpiece, whereby the inserted portion ofthe tubular electrode and the internal surface of the hole compriseelectroplating electrodes; connecting an inlet end of the tubularelectrode to a supply of plating solution to direct a flow of platingsolution through the tubular electrode, out of the discharge outlet,between the anode and interior surface of the hole, and out of an openend of the hole, whereby metal is deposited from the flow of platingsolution onto the interior surface of the hole and the plating solutionflow is continuous during a predetermined hole plating procedure; andcollecting spent plating solution flowing out of the open end of thehole in a collection device spaced below the plating system during holeplating, and directing the spent plating solution along a discharge flowpath away from the workpiece and tubular electrode.
 2. The method ofclaim 1, wherein the workpiece has at least one electrical terminal, andthe hole is a first solder cup at one end of the electrical terminal. 3.The method of claim 2, wherein the workpiece is an electrical or hybridelectro-optical connector.
 4. The method of claim 2, wherein theworkpiece is a finished electronics assembly including one or moreconnectors having multiple electrical terminals each having a solder cupat one end of the electrical terminal.
 5. The method of claim 1, whereinthe tubular electrode comprises a needle anode and the hole to be platedis configured to act as a cathode when the power supply is connectedbetween the needle anode and workpiece.
 6. The method of claim 5,wherein the needle anode is of noble metal material.
 7. The method ofclaim 2, wherein the tubular electrode comprises a needle anode having afirst diameter less than the diameter of the solder cup, whereby theplating solution flow path through the solder cup includes an annularspace of predetermined width between an outer surface of the needleanode and the inner surface of the solder cup to be plated.
 8. Themethod of claim 7, wherein the solder cup has a bore diameter of lessthan 0.25 inches and a depth-to-width aspect ratio of at least 2.0. 9.The method of claim 8, wherein the ratio of the needle anode radius tothe hole radius is approximately 0.6.
 10. The method of claim 8, whereinthe ratio of needle anode radius to hole radius is in the range fromaround 0.1 to 0.6.
 11. The method of claim 7, wherein the width of theannular space between an outer surface of the insertion portion andinner surface of the solder cup is in the range from 0.01 to 0.04inches.
 12. The method of claim 7, wherein the predetermined spacingbetween the needle anode and inner end of the solder cup in the platingposition is approximately two times the diameter of the insertionportion of the needle anode.
 13. The method of claim 12, wherein thepredetermined spacing is in the range from 0.04 to 0.06 inches.
 14. Themethod of claim 2, wherein the workpiece has a plurality of electricalterminals each having a respective solder cup at one end.
 15. The methodof claim 14, further comprising terminating plating solution supply tothe first solder cup after plating the inner surface of the first soldercup, moving the needle anode out of the first solder cup to a positionwhere the discharge outlet is spaced above the open end of the firstsolder cup, moving the needle anode to a position above and centeredover a second solder cup to be plated, moving the needle anodevertically until the insertion portion extends into the second soldercup with the discharge outlet spaced a predetermined distance above theinner end of the second solder cup, repeating the plating steps untilthe inner surface of the second solder cup is plated, and repeating theforegoing steps until all solder cups of the metal object requiringelectroplating have been plated.
 16. The method of claim 1, wherein thecollection device comprises a basin of non-conductive, semi-rigidelastomeric material, wherein the step of supporting the workpiecefurther comprises sealably engaging at least one opening in a lower wallof the collection basin over at least part of the workpiece spaced belowthe open end of the hole to be plated prior to commencing plating. 17.The method of claim 16, wherein the workpiece comprises a connectorhaving a plurality of electrical terminals having terminal portionsprojecting out of an insulating body of the connector, each terminalportion having a solder cup at its outer end.
 18. The method of claim17, wherein the step of sealably engaging the collection basin to theworkpiece comprises sealably engaging a plurality of openings in thelower wall of the collection basin which are of smaller diameter thanthe terminal portions of the electrical terminals over the terminalportions at a location spaced below the open ends of the respectivesolder cups.
 19. The method of claim 18, further comprising engagingnon-conductive masking sleeves over terminal portions of the electricalterminals extending through said plurality of openings, whereby outersurfaces of the conductive terminal portions are shielded from spentplating solution flowing out of the open end of a respective solder cupduring plating of the solder cup.
 20. The method of claim 19, whereinthe masking sleeves are formed integrally with the respective openings.21. The method of claim 19, wherein the masking sleeves are formedseparately from the basin and engaged separately over said terminalportions.
 22. The method of claim 18, wherein the step of collectingspent plating solution comprises directing plating solution flowing intothe collection basin during electroplating of one of the solder cups outof a drain hole in the lower wall and into a discharge pipe fordirecting spent plating solution away from the plating system.
 23. Themethod of claim 17, wherein the step of connecting a power supply to thework piece includes electrically connecting the electrical terminalsseparately to the power supply.
 24. The method of claim 23, furthercomprising connecting the electrical terminals, a body of the workpiece,and a ground together as a common node.
 25. A method for electroplatingan interior surface of a blind hole in a workpiece, the methodcomprising: electrically coupling a first power supply terminal to anelectroplating anode, the electroplating anode including a platingsolution inlet, a discharge outlet, and a passageway within theelectroplating anode extending between and fluidly coupling the platingsolution inlet and the discharge outlet; positioning at least an endportion of the electroplating anode extending up to the discharge outletwithin the interior surface of a blind hole in a workpiece which is atleast partially formed of conductive material including the blind hole,with the end portion spaced from the interior surface and an inner endof the blind hole; electrically coupling a conductive portion of theworkpiece including the blind hole to a second electrical terminal ofthe power supply; fluidly coupling a plating solution supply to thedischarge outlet via the plating solution inlet and the passageway;directing plating solution in a plating flow path from the platingsolution supply through the internal passageway, out of the dischargeoutlet, through a space between the interior surface of the blind holeand the outer surface of the inserted end portion of the electroplatinganode, and out of an open upper end of the blind hole; and establishingan electric current between the interior surface of the blind hole andthe electroplating anode through the plating solution such that metal isliberated from the plating solution and attached to the interior surfaceof the blind hole.
 26. The method of claim 25, wherein the workpiece hasat least one electrical terminal, and the blind hole is a first soldercup at an end of the electrical terminal.
 27. The method of claim 26,wherein at least the inserted portion of the electroplating anode has apredetermined outer diameter of no more than 0.6 times the diameter ofthe solder cup.
 28. The method of claim 26, wherein the solder cup has adepth-to-width aspect ratio of at least 2.0.
 29. The method of claim 26,further comprising collecting spent plating solution flowing out of theopen end of the solder cup in a plating solution drain of insulatingmaterial engaging over the first electrical terminal at a locationspaced from the open end of the solder cup.
 30. The method of claim 25,wherein the workpiece comprises a connector having a connector body anda plurality of electrical terminals each having a solder cup at an endof the respective electrical terminal, the method further comprisingmoving the end portion of the electroplating anode out of a first soldercup after completion of electroplating, moving the electroplating anodeinto position over a second solder cup, positioning the end portion ofthe electroplating anode in the second solder cup, directingelectroplating solution in the flow path out of the discharge outlet ofthe electroplating anode and through the space between the anode andsolder cup to electroplate the second solder cup, and repeating theforegoing steps until each solder cup is electroplated.
 31. The methodof claim 30, wherein the step of electrically coupling a secondelectrical terminal of the power supply to the conductive portion of theworkpiece includes electrically connecting the plural electricalterminals of the connector, the connector body, and a ground together asa common node.